CA2480134A1 - Probe-car system using beacon and apparatus therefore - Google Patents
Probe-car system using beacon and apparatus therefore Download PDFInfo
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- CA2480134A1 CA2480134A1 CA002480134A CA2480134A CA2480134A1 CA 2480134 A1 CA2480134 A1 CA 2480134A1 CA 002480134 A CA002480134 A CA 002480134A CA 2480134 A CA2480134 A CA 2480134A CA 2480134 A1 CA2480134 A1 CA 2480134A1
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- information
- beacon
- probe
- car
- measurement
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/01—Detecting movement of traffic to be counted or controlled
- G08G1/0104—Measuring and analyzing of parameters relative to traffic conditions
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C5/00—Registering or indicating the working of vehicles
- G07C5/008—Registering or indicating the working of vehicles communicating information to a remotely located station
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C5/00—Registering or indicating the working of vehicles
- G07C5/08—Registering or indicating performance data other than driving, working, idle, or waiting time, with or without registering driving, working, idle or waiting time
- G07C5/0841—Registering performance data
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- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Traffic Control Systems (AREA)
Abstract
The present invention provides a probe-car system in which beacons are used to efficiently collect measurement data from an FCD on-vehicle apparatus. There are provided an on-board unit of a probe-car 121 which selects one of second information (1) of measurement information measured during running and road section reference data indicating a measurement section of the measurement information and first information (3) of the measurement information, and uploads it to a beacon 123, and a center apparatus which collects the measurement information from the on-board unit of a probe-car 121 through the beacon 123. In this system, when the probe-car 121 runs along an installation route of beacons 122 and 123 and passes through under the downstream side beacon 123, only the measurement information is transmitted, so that the data amount of the measurement information can be increased, and the detailed measurement information can be transmitted. When the probe-car 121 runs along a bypass, the swept path of the bypass and the measurement information are uploaded to the downstream side beacon 123, so that the center apparatus can utilize it as the measurement information of the bypass.
Description
Probe-Car ~ystera Using seaeon and Apparatus Therefore Background of the Tnvention Field of the Tnvention s The present invention relates to a probe-car system which collects measurement data measured while a car is moving and utilizes it fow traffic information and an apparatus therefore, and particularly to a probe-car system which enables measurement data to be efficiently collected to through a beacon and an apparatus therefore.
Description of the Related Art In recent years, an investigation has been made on the introduction of a probe-car system (also called a is floating car data (FCD) system) using a running vehicle as a s@nsor (probe) for collecting traffic information. In this system, an FCD on-vehicle apparatus installed in a vehicle records the speed of the vehicle and the swept path thereof, and transmits them to a center. In the center, za . measurement data transmitted from respective vehicles are analyzed to create road traffic information relating to traffic flow and the like.
Qatent document 1 (gyp-A-2002-269659) discloses a probe-car system in which a center specifies a collection zs area of FCD, an FCD on-vehicle apparatus of a vehicle running zn this area measures and stores a running position, a running speed az~d the like at every unit time, and the stored measurement data is transmitted to the center by usincr a cellular phone at e~rexy regular time S period.
However, in the probe-car system using the cellular phone, it becomes a serious problem who bears the communication cost. In the case where the center bears the communication cost, the cooperation of the FCD on~vehicle so apparatus side is easily obtained, and it is expected that a large amount of measurement data are collected. However, the burden of the center becomes severe. On the other hand, when the FGb on-vehicle apparatus side is forced to bear the communication cost, it becomes difficult to i5 collect a large amount of data.
Summary of the Invent.~.on The invention solves the conventional problem as stated above, and an object thereof zs to provide a probe~-2o car system in which beacons used for providing traffic information are utilized to efficiently collect measurement data from an FCD on~vehi.c~.e apparatus, and an apparatus for constructing the system.
A probe--car system of the invention includes an on-~s board unit of a probe-car which selects one of second z information of measurement information measured during running and road section xefererce data ~,ndicating a measurement section of the measurement informat~.on and first xn~ormation of the measurement information, and s uploads it to a beacon, and a center apparatus which collects the measurement information from the on-board unit of a probe-car through the beacon.
Besides, an on-board unit of a probe-car of the invention includes a communication unit for communicating ~.o with a beacon, an own vehicle position judgment unit for detecting own vehicle position, a sensor information collection unit fox collecting measurement information of a sensor, a storage unit for stor~.ng the measurement Information collected by the sensor information collection is unit and a swept path made of a sGt of the own vehicle position detected by the own position judgment unit, a coding process~.ng unit for transforming the measurement information and the swept path stored in the storage unit into coded data, an informat~.on transmission. unit for 2o transmitting the coded data of the one of ,the second information ~.~acluding the measurement ~.n,~ormation and the swept path arid the first information the rneasurernent information, to the beacon, when passing through the beacon, and an instructir~n informat~.on reception unit for as receiving instruction information including izzstructions of a measurement method of the measurement inforrna~tion and a coding method of the coded data from the beacon.
In this system, when the probe-car runs along an installation route of beacons and passes through under a downstream side beacon, only the measurement. information is s uploaded, so that the data amount of the measurement information can be increased, and the detazled measurement information can be transmitted. When the probe-car runs along a bypass and passes through under a downstreaza sl.de beacon, the swept path of the bypass and the measurement ~o information are uploaded. so that the center apparatus can utilize it as the measurement information of the bypass.
Brief Description of the Dxavafngs is Fig. 1 is a view showing a data structure of transm.itted/received data in a probe-car system according to a first embodiment of the invention;
Fig. 2 is a block diagram showing a structure of the probe~car system according to the first embodiment of 2o the invent~.ox~,;
Fig. 3 is a flow chart showing an operation of the probe-car system according to the first embodiment of the invention;
Fig. 4 is a view showing a relation between z5 ox~.g~.nal data and a first order scaling coefficient;
Fig. 5 is a view Showing a relation among first order, second order and third order scal.ang coefficients;
Fig. 6 ~.s a view showing gez~exal expressions of wavelet transform;
Flgs. 7A and '7B are views showing filter circuits for realizing AWE;
Fig. 8A is a view show~.ng separation of a signal in DWT and Fig. 8~ zs a view showing reconstruction of signals in IDW'F;
to Figs. 9A and ~B are views showing filter circu~.ts realizing the DWT and the IDWT in the first embodiment of the invention;
Figs. 10A to lOC are explanatory views of road section reference data;
is Fig. 11 zs a view showing a data structure of transmitted/xeceived data in a probe-car system according to a second embodiment of the ~.nvention:
Fig. 12 is a block diagram, showing a structure of the probe--car system according to the second embodiment of 20 the invent~o~l;
Fig. 13 is a flow chart showing an operation of 'the probe-car system according to the second embodiment of the invention;
Fig. 14 is a view showing a data structure of 2s transmitted/received data in a probe-car system according to a third embodiment of the invention; and Fig. 15 is a flow chart showing an operat~.oh of the probe-car system according to the third embodiment of the invention.
s In the drawings, a reference numeral 80 refers to a center apparatus; 81 to a swept path measurement information utilization part; 82 to a coded data decodi.n.g part; 83 to a fCD ~.nfoxznat~.on reception part; 84 to a measurement coding instruction transmission part; 8S to a to measurement coding instruction selection part; 86 to a measurement coding ar~stxuct~.on data; 87 to a beacorx communication part; 90 to an on-board unit of ~. probe-car;
91 to a FCD information transmission part: 92 to a FCD
informati.ox~ selection part; 93 to a coda-ng processing part:
is 94 to a measurement coding xnstxuct~.on reception part; 95 to a measuremEnt coding instruction data: 96 to a default measurement coding instruction data; 9'7 to an own vehicle position judgment part; 98 to a swept path measurement information storage part; 99 to a sensor information 20 COlleCtl.On part; 100 to an on-vehicle apparatus communication part; 101 to a GPS antenna;102 to a gyro; 106 to a sensor A; 107 to a sensor B; 108 to a sensor C; 121 to a probe-car; 122 to an u~astream side beacon; 123 to a downstream side beacon; 183 to a low-pass filter; 1,82 to a 2s high-pass filter; 18~ to a thznn~.ng circuit; 184 to a low-pass filter; 3.85 to a high-pass filter; 185 to a thinning circuit: Z87 to an adder circuit; 191 to a filter circuit:
192 to a filter circuat: and 193 to a filter circuit.
Detailed Descrzpgion o~ the preferred Embodiments xn a probe-car system of an embodiment of the invention, measurement information measured by a probe-car is collected through a beacon.
At present, beacons are installed an a road in order to provide VICS road traffic information to a passing vehicle at a pinpoint. The beacons have two Types, that io is, an optical beacon for a general road and a radio beacon for ar. expressway. For example, in the case of the optical beacon, two-way communication with an on-vehicle apparatus can be performed at a data transfer speed of 1 Mbps.
Although a distance between beaGOns varies according ~o an is installation state or the like, it is about several hundred m to several Km.
(First Embodiment) Tn a probe-car system of a first embodiment of the 2o invention, a swept path and measurement information of speed, fuel consumption and the like are measured by a probe-car, and when the probe-car first passes through under a beacon, or passes through under a next beacon after a specified time has passed since the probe-car passed z~ through under the last beacon for after running a specified ., distance or more), the measurement information and the swept Bath data are uploaded as FCD information from an on-board un~.t of a probe-car through the beacon. The scaept path data has a meaning as road section refex-ence data s indicating an object road section of the measurement infoxmat~.on.
A center apparatus haring received the FCD
information specifies the object road section of the measurement information from the swept path data, and utilizes the measurement information for the creation of traffic in:~ormation of the object road section.
When the probe-car passes through under the next bt~acon within the specified time since it passed through under the last beacon (or before it runs the specified' distance?, the travel distance and the number of the last passed beacon, togefi,her with the measurement information, are up~.oaded as the road section reference data from the on-board unit of a probe-car.
T'he center apparatus having received the FCD
2o inforinat~.on regards the probe-car as having run along the installation route of the beacons in a case where the travel distance and the installation distance between the beacons are substantially coincident with each other, and utilizes the measurement information for the creation of 2s the traffic information of the route. On the other hand, in the case where the travel distance and the installation distance between the beacons are much different from each other, the center apparatus rEgards the probe-car as having run slang a bypass, and stops the use of the measurement information.
s Respective processings will be described ~.n deta~.J..
<Cxeation of Running Locus Data>
position data at every regular distance L (for example, 20o m) is sampled from t~Ze posit~.on data measured so by the probe-car during running, the position data at the respective sampling points (.nodes) are arranged in seq~:ez~ce, and the node row is made the swept path data. and is transmitted to the center apparatus. At this time, in order to decrease the data amount of the swept path data, a is . following processing is performed.
First, 'the position data of a sampling point (node) is expressed by an argument 8 from an adjacent node. When a measurement start point or an end point is made a reference point, and the position of the reference point is zv specified by latitude and longitude, and when L is made canstant, the position of each node can be specified by only the argument 8. Next, the positian data is transformed into data haring a bias statistically. For tk~at purpose, when an argument from an adjacent node oz a z5 noticed node is made 8;, the position. data of the node is expressed by a difference between an argument predicted g value of the node predicted by using arguments 8~_~, and 6y_~
of preceding nodes (stat~.stical predicted value: for example, (8~_1 + 0~_2) !2) and the argument 8~ . l~ext, the data Qf the node row expressed by the argument predicted s difference value is subjected to variable length cod~.ng on the basis of a code tab3.e, and the coded data is transmitted to the center apparatus through the beacon.
when receiving the swept path data, the center apparatus decodes the coded data by using the same code so table, and decodes the arrangement of the position data of the nodes. Map matching of the arrangement of the nodes and the own map data is performed, and the swept path data of the probe-car i,s specified can the own map data.
is <Cx~eat~.on of Measurement Tnformation~
,Ia~.so with respect to the measurement information of speed, fuel cons~unptioz~ and the lilze, coding is made in order to reduce the data amount. l~ex~e, a descript~.on will be given. to a case where sampling data of the measurement zo information is supjected to discrete wavelet transform (DWT) to code the measurement information.
hig. 6 s~aows general expressions of the wavelet transform. The waveiet is a set of functions such as (mathematical expression 3) which is formed by performing z5 an operation (scale transform) of magnifying a function 'Y (t) , which is called a basic wavelet arid exists only in a 3. 0 limited range in time and frequency, by a factor of a on a time axis, or an operation {shift transform) of sh~,ft~.ng it by b in time. The firequenoy and time components of a signal corresponding to the parameters "a" and "b°' can be s extracted by using this function, and this operation is call the wavelet transform.
The waveJ.et transform zz~c7.udes a continuous wavelet transform and a discrete wavelet transform (DWT). The forward transform of the continuous wavelet transform is o expressed by (mathematical expression 1), and the inverse transform thereof is expressed by (mathematical expression 2), when the real numbers a and b are made a = 2j and b =
2jk ( j > 0) , the forward txaz~sform of the discrete wavelet transform is expressed by (mathematical expression 5), and u5 the inverse transform (IDWT) is expressed by {mathematical expression 6).
The DWT can be realized by a filter circuit for recursively d:.vidi.ng a J.ow frequency, and the wIDWT is realized by a filter circuit repeating synthesis inverse to zo the time of division. Fig. 7A shows the filter circuit of the DwT. The DWT circuit is constructed of plural caseade--connected circuits 19J., 192 and 193 each including a low pass filter 181, a high-pass filter 182, and a thinning circuit 183 fax thinning out signa~.s to J./2. The high zs frequency component of a signal inputted to the circuit 191 passes through the high-pass filter 182, is thi.nz~ed out by the thinning circuit to 1/2, and is outputted. The low frequency component thereof passes through the low--pass filter 181, is th~,nz~ed out by the thinning circuit to 1/2, and is inputted to the next cixcuit 192. Similarly, a~.sa s in the circuit 192, the high frequency component is thinned out and is outputted, and the low frequency component is thinned out, is inputted to the next circuit 193, and is similarly divided into a high frequency componer_t anal a low frequency component.
to Fig. 8A shows signals decomposEd by the respective circuits 191, 192 and 193 of the DWT circuit. An input signal f(t) (--- Ski°a; a superscript denotes the order) is divided in the circuit 193 into a signal. Wk;1? having passed through the high~pass filter 7.82 anci a signal Sk~l~ having is passed through the low-pass filter 1~~1. The signal. Sk~2~ is divided in the next circuit 92 into a signal wk~2? having passed through the high-pass filter 182 and a signal Sk{'~
having passed through the low pass filter 18v. The Sk~2~ is divided in the next circuit 193 zntc> a signal Wkt~~ having 2o passed through the high.-pass filter 182 and a signal Sk°3a having passed through the low-pass filter 187.. The S(t) is called a scaling coefficient (or low-pass filter), and W(t) is called a wave7.et coefficient (or high--pass filter) .
Next (mathematical expression B) and (mathematical. I
2s expression 9) indicate transform expressions of the DWT
usEd in the embodiment of the invention.
step 1: wt (t) - f (at~i) ~ C { f (2t) + f (2t~z) ~/2) (mathezn~atzca7. expression 8) step 2: s (t) - f (2t) + j (w(t) + w(t-1) + 2}/9]
(mathematical expression 8) s Tn the first order forward transform, sampling data of the measurement ~.nfoxmatian is made the discrete vaJ.ue f(t), and is transformed by the (mathematical expression 8) and the (mathematical expression 9) into the first order wavelet coefficient and the first order scaling so coefficient. zn a subsequent nth order forward transform, an (n-1)th order scaling coefficient is made f(t), and transform into an nth order waveiet coeff~.cient and nth order scaling coefficient is performed by the (mathematical expression 8) and the (mathematical expression 9). Fig, 9A
is shows a structure of each of the circuits 191, 192 and ?.93 of the DWT circuit reaiizing this transform. zn the drawing, "Round" indicates a rounding processing. The sampling data (state amount) of a traffic w state is transformed into the scaling coefficient and the wavelet zo coefficient by the (mathematical expression 8) and the (mathematical expression 9) and is p~.~ovided.
Fig. 7B shows a filter circuit of the IDWT. The TDWT circuit is con.stxucted of plural cascade-connected circu~.ts 194. 195 and 196 each including an interpolafiion zs circuit 186 for interpolating a signal by a factor of 2, a low-pass filter 184, a high-pass filter 185, and an adder 1~
187 for adding outputs of the low-pass filter 184 and the high-pass filter 185. Signals having a high frequency component and a low frequency component inputted to the circuit Z94 are interpolated by a factor of 2, are added to s each other, are inputted to the next circuit 295, are added with a high frequency component in this circuit 195, are further added with a high frequency component in the next circuit 195, and are autputted.
Fig. 8~ shows signals reconstructed by the circuits l0 194, 7.95 and 196 of the TDWx c~.rcuit:. In the circuit 194, the scaling coefficient Sk~3~ and the wavelet coefficient Wk~3~ are added to each other, so that the scal,~.ng coefficient Sk~Zf is created. In the next circuit 195, the sca7.ing coefficient Sk~2r and the wavelefi coefficient Wk~z~
xs are added to each other; so that the scaling coefficient Sksl~ is created. In the next circuit 196, the scaling coefficient Sk{1~ and the wavelet coefficient Wk«~ are added to each other, so that the Ski°' (= f(t)) is created.
Next (mathematical expression 10) and (mathematical 2o expression 11) indicate transform expressions of the TDWT
used in the embodiment of the inrrenti.on.
step ~.: f(~t) - s(t) + [~w(t) * w(t-1) ~- 2}/4~
(mathematical expression 10) step 2: f (2t*1y ~ w(t) - [~f(2t) * f(Zt+2) }/2a 25 (mathematical expression 11) Tn the nth order inverse transform, the signal f(t) transformed by (nø1)th order IDWT is made the scaling coefficient, and the transform with the stEps of the (raathEmatical expression 10) a~zd the (mathematical expression 11) is performed. Fig. 9~ shows a structure of each of the circuits 194, 195 and lg5 of the IDWT circuit for realizing this transform.
A.s stated above, from the sampling data of the measurement informat~.on, the scal.~.rag coefficient and the wavelet coefficient can be ca~.culated by the (mathematical so expressian $) and the (mathematical expression 9).
Besides, from the scaling coeffzc:ient and the wavelet coei~ficient, the sampling data of the measurement information. can be restored by the (mathematical expression 10) anal the (mathematical expression 17.) .
The first order scaling coefficient smoothes and indicates the shape expressed by the sampling data (original data), and the nth order scaling coeffic~.ent smoothes and indicates the shape expressed by the (n-~1~) th order scaling coefficient. In Fig. 4, the ~rertical axis 2o indicates speed, the horizontal axis indicates distance from a reference point, the sampling data of speed measured by the probe-car is indicated by a solid line, and the first scaling coefficient obtained when the original data is subjected the DWT once is indicated by a dotted line.
zs Fig. ~ shows the first scaling coeff~.cient (dotted line), a second scal~.ng coefficient (dashed line) obtained when the 7. 5 DWT is further repeated, and a third scaling coefficient tdotted line with long ling portions). The distance interval between the first order scaling coefficients is twice the distance interval of the original data, and the s value of the scaliing coefficient is an average of the values of the original data included in the distance interval. ?'he distance interval between. the nth order scalzng coefficients is twice the distance interval between the (n-1)th order scaling coefficients, and the value of to the nth order scaling coefficient i$ an average ofi the vaJ.ues of the (n-1)th order scaling coefficient included in the distance interval.
Accordingly, even in the case 'where the amount of data uploaded from the on-board unit of a probe--car is 15 limited, when data capable of restoring the nth (n ~ 1, 2, scaling coefficient as transz~itted, the center apparatus can grasp the rough state (coarse measurement information) of the measurement inf~~rmation,. ~As the order of the scaling coeffac~.ent becomes high, the amount of data ao transmitted from the on-board unit of a probe-car is decreased, and the measurement information which can be grasped by the center apparatus becomes coarse.
~cTransmitted/Reeeived Data Structuxe>
z5 Fig. 1 exemplifies a data structure of data transmitted and received between the on-board unit of a probe-car and the beacon.
When a probe-car i21 first passes through under a beacon 122, or passes through under the beacon 122 after a specified time has passed since it passed through under the s last beacon (or after it travels a specified distance), FCD
information ("swept path * measurement information'P) indicated by (1) is transmitted from the on-board unit of a probe-car to the beacon 122. The information includes the identification number of a code table used for encoding of ;o swept path, sampling distance interval of position information indicating the swept path, distance interval of the measurement information, coded data indicating the swept path, and coded data of the measurement information subjected to the DWT transform.
15 Since the position Information of the beacon 122 as the reference paint (end point) of the swept path is already known in the center apparatus, it is not necessary w that the position information of the reference point is w included in the data indicating the swept path.
zo Nevertheless, since the data amount of the coded data indicating the swept path is large, it is necessary to lessen the data amount of the coded data of the measurement information in the FCD Information c>f (1}. Thus, measures are taken such that only data necessary fox restoring the zs nth prdex scaling coefficient is made to be includEd, the sampling distance Interval of the measurement information is expanded to roughen the accuracy o~ the measurement information, or the distance of the sectzon as the object of the measurement information is narrowed.
~On the other hand, the beacon 7.22 downloads s ~.nstruction information indicated by (2) to the on-board unit of a probe-car passing through under the beacon 122.
The information includes the beacon number of the beacon 122, instruction information of the measurement method and coding method of the measurement information (information xo of the number of the measurement method and coding method previously transmitted to the on--board unit of a probe-car, and a code table used for coding), sampling distance znterval of the measurement information, and 'the like_ when the probe-car ~.2~. passes through under a ~s downstream side beacon 123 within the specifa.ed time since it passed through under the upstream side beaGOn 122 (or before it runs the specified distance), FCD information ("travel distance + measurement information") indicated by (3) is transmitted from the on-board unit of a probe--car to zo the beacon 123. This information inc3.udes the number of the last passed beacon 7.22, the travel distance from the ~.ast passed beacon x.22, the instruction number of the measurement method and cod~.ng method recei~red from th.e 'last passed beacon 122, the sampling distance interval of the 2s measurement information, and the coded data of the measurement information subjected to the DWT transform.
5i.nce the FCD information does not include the data o~ the swept path, the data amount c~f the coded data of the measurement information can be increased, and the infoxznation accuracy of the measurement information can be s raised.
.System Structure>
Fig. 2 shows a structure of this probe-car system.
This system includes an on-board unit 90 of a probe-car, ~o for measuring and providing data at the time of running, and a center apparatus 80 for collecting the data through a beacon. The beacon itself may have the structure of the center apparatus 80.
The onboard unit 90 ir.~cludes an on-~rehicle is apparatus com.~nunacatidn part 100 :Eor performing two-way communication with the beacon, a measurement coding instruction reception part 94 fox receiv~.ng ir_stxuction information. from the beacon, a~ sensor information cc~lleGti.on part 99 for collecting measurement ~.nformat~.on zo of a sensor A 10~ for detecting speed, a sensor H 107 for detecting power output, a sensor C 108 for detecting fuel consumption, and the like, an own vehicle position judgment part 9? for detecting own vehicle position by using GPS
information received by a GPS antenna 10~. and information zs of a gyro 102, a swept path measurement information storage part 98 for storing the swept path of the own vehicle and the measurement information of the sensors A, H and C, a coding processing part 93 for coding the measurement ~.nformation and sampling data of the swept path on the basis of instruction data 95 of the measurement method arid s coding method rece~.ved from the beacon and instruction data 96 of the default measurement method, and coding method pre~riously held by the on-board unit ~0, an FCD information selection part 92 for selecting whether the FCD information (1) of Fig. 1 is to be transmitted tc> the beacon or the FCD
to informata.on of (3) is to be transmitted, and an FCD
~.nformation transmission part 91 for. transmitting the FCb information selected by the FCD information selection part 92 to the beacar_ when passing through, under the beaGan.
pn the other hand, the center apparatus 80 includes 15 a beacon communication part 87 for perfarmin,g two-way communication with the on-board unit 90, an fD information reception part 83 for receiving the FC1~ information from the on-board unit 90, a coded data decoding part 82 for decoding the coded data included in the F'CD information, a 2o swept path measurement information utilizing part 81 for utilizing the data of the decoded measurement information and swept path, a measurement coding instruction selection part 85 for selecting measurement coding instruction data 86 to be gi~rer. to the on-board unit 90, and a measurement 25 COdl~I7g ~.nstruction transmission part 84 fior transmitting the selected measurement coding s.nstruct~.an data 86 to the on-board unit 90.
zn the center apparatus 80, there are prepared the plural measurement coding instruction data 86 made to correspond to traffic states and each including the s measurement method and coding method of the measurement information, the information of the code table, and the like. When the beacon communication part 87 starts the two-way communication with the on-board unit 90, the measurement coding instruction selection part 85 selects io the measurement coding instruction data 86 Corresponding to the present traffic state, arid the selected measurement coding instruction data 86 is transmitted to the on~bard unit 98.
is <Processing Flow>
dig. 3 shows a processing flow of the probe-car system. The on-board unit 90 measures present position and speed (measurement information) in a unit of, for example, one second, and stores the measurement data in the swept zo path measurement information storage part 98 (step 1). The coding processing part 93 creates sampling data of sampling distance interval of position information and creates coding data expressing the swept path from the stored swept path data in accordance with the measurement coding z5 instruction data 95 when the instruction data has been received from the beacon, or in accordance with the default measurement coding instruction data 96 if not so. Besides, the coding processing pant creates, from the stored speed information, the sampling data of sampling distance interval of the measurement infozmation, and creates coded data of speed information subjected to the CWT transform (step 2) .
text, the coding process~,nc~ part 93 creates th.e data of travel distance from the last passed beacon, and creates tk~e coded data o~ speed information subjected to so the DWT tr ansform ( step 3) .
The FCD information se~.ection part 92 counts up an accumulation counter for counting the accumulated value of distance (or time) froze the last passed beacon, and when the count value of the accumuJ.ation counter exceeds a is specified value, the "swept path ~ measurement information"
((1) of Fig. 1) created at step 2 is determined to be the transmission data. When the count value of the accumulat~.on counter is the specif~,ed value or less, the ~~travel distance + measurement information" ((3) of Fig. 1) 2o created at step 3 is determined to be the trans~uisszon data (step 9) .
In the case where the on-vehicle apparatus communication paxt 100 starts the communication w~.th the beacon coz~.munication. part 87, the FCD information z5 transmission part 9J. judges that the timing of transmission occurs (step 5), and transmits the FCA information selected by the FCD information selection part 92 to the beacon (step 6) . When the tiz~,ing of transmission does not occur, the procedure from step ~. is repeated.
After transmitting the FCD information to the s beacon, the on-board unit 90 resets the accumulation .counter, and resets the data stored in the swept path measurement information storage part 98 (step 7).
When receiving the FCD a.nformation (step 20), the cex~tex apparatus 80 transmits the new measurement and io coding instruction data 86 selected by the mEasurernent coding instruction selection part 85 to the on-board unit 90 (step 21). The on,-board unit 90 receives the new measurement coding instruction data (step 8), and repeats the procedurE from step 1.
is In the case where "swept path a~ trie~.sur ement information" ((1) of Fig. I) is received, the center apparatus 80 refers to the pertinent measurement and coding instruction data, decodes the coded data, and reproduces the measurement information on the swept path. In the case zo where "travel distance + measurement information" ((3) of Fig. 2) is received, the center apparatus refers to the travel distance and the beacon number included in the FCD
information. When the installation interval between the upstream side beacon and the downstream side beacon is 2s substantially coincident with the travel. distance, the center apparatus refers to the pertinent measurement and coding instruction data, decodes the coded speed data, and reproduces the speed information whi3e the installation route of beacons is made the swept path (step 22).
The center apparatus 80 utilizes the reproduced s speed information for creation of the traffic information and the like (step 23).
As stated above, in the probe-car system, the FCD
information can be efficiently collected from the on-board unit by using the beacon.
io Modified Example>
Although the description has been given to the case where the variable 2ength coding system of an argument predicted difference value is applied to the coding of the is swept path data, and the coding system by DWT is applied to the coding of the measurement information, the invention is not limited to this. The measurement information can be coded by the variable length coding system of the argument predicted difference value, and the swept path data can be zo coded by the DWT. Besides, it is also possible to use orthogonal transform such as DFT (discrete Fouriex transform), DGT idiscrete cosine transform), DHT (discrete Hadamard transform), or DWT (discrete wavelet transform).
Besides, although the description has been given to 2s the case where the measurement and coding instruction data is downloaded from the beacon to the on-board unit, this is not inevitabJ.e, Besides, a~.though the description has beer. given to the case where the swept path data is transmitted as the road section reference data ind~.ca,ting the object z~oad s section of the measurement information, the road section reference data may be othexs» For example, as shown in Fig. 10A, un~.formly determined road section identifiers (link number) and intersection identifiers (node number) may be used.
to zz~ the case where both the on-board unit and the center apparatus refer to the same map, the on-board unit transmits the latztude and longitude data of the measurement start ~aoint on the map to the center apparatus, and the center apparatus can specify the road section based on this data.
Besides, as shown in fig< IO:B, the abject road may be transmitted by transmi.tt~.ng latitude and longitude data (including the attribute information of name, kind of road and the 7.zke as well) for position reference of zg interm~.ttent nodes P1, P2, 1~3 and P~~, which are extracted from intersection parts and roads at midpoints in the link, to the centex apparatus. Here, the nodes are as follows:
P1 - link center point, P2 = zr~tersection part, p3 = 1. ink center point, and P4 = link center point. Zn this case, as zs Shawn i.n Fig. IOC, the oenter apparatus specifies the respective positions of Pl, P2, P3 and P4, and next, COhneCt9 the respective sections by a route search to specify the cbject road section.
Besides, as the road section reference data fox specifying the object raad, a road map is divided into s tile-~li.ke parts, and identifiers attached to the respective ones, kilo posts provided on the road, road name, address, zip code and the ZiJ~e may be used.
Movement distance, movez~ent time, exhaust gas information, wiper operation state, parking brake operation la state and the like in addition to the speed, the power output, and the fuel consumption can be included in the measurement informatian.
(Second ~mbodzment) xs In a probe-car system of a second embodiment of the invention, when a an--board unit of a probe-car having passed through under an upstream side beacon passes along a previous3y determined xoad and reaches a~ downstream side beacon, only measurement information is uploaded to the za downstream side beacon, and when passing along another road and reaching the downstream s~.de beacon, swept path data and the measurement information are uploaded to the downstream side beacon. In order to enable the on-board unit itself to discrim~.nate whether it has passed along the z5 previously determined road, the upstxeam side beacon transmits the number of the downstream side beacon and the distance to the downstream side beacon to the on-board unit. When the on-board unit reaches the downstream side beacon, in the case where the travel distance is substantially coincident with the distance to the s downstream .side beacon transmitted from the upstream side beacon, the on-board unit discrimina°tes that it has passed along the previously determined road, and when the travel distance is much different from the dzstance to the downstream side beacon transmitted from upstream side so beacon, the on-board unit discriminates that it has not passed along the prev~.ous3y deterrnine:d road.
Fig. 17. exemplifies the data structure of data transmitted and received between the on-board unit and the beacon.
Data (1) "swept path * measurement z,nformation~~ is FCD information uploaded from the on-board unit to the downstream side beacon ~.2~ when the probe~car 121 reaches the downstxeaxn side beacon 123 without passing along the prev~.ously determined road. This is the same as the FCD
zo information transmitted from the on-board unit fid the beacon 122 in the fzrst embodiment (~'ig. ~.) when the probe-car ~.2~, first passes through under the beacon I,22, or passes through u_~nder the beacon 122 after the specified time has passed since it passed thxough under the last 2s beacon (or after it runs the specified distance or more).
Data (2) "instruction informat~.oz~ to probe-car" is - CA 02480134 2004-09-O1 - . , ,."
~.nstruction information transmitted from the downstream side beacon 122 to the on-board unit. 'this informati.an includes information of the number of the downstream side beacon 123, and the distance to the beacon 123 in additior_ s to the beacon number of the beacon 122, instruction information of x~.easurement method and cading method, and saz~pli,ng distance interval of measurement informatian.
Data (3) "only measurement information" is FC1~
informati.an upJ.oaded from the on-board unit to the to downstream side beacon 123 when the pxobe-car 121 passes along the pre~riously determined road and reaches the downstream side beacon 123. This is the same as the FCD
iz~foxzn.ation. transmitted to the downstream side beacon 123 in the first embodiment (Fig. 1) when the probe~car 121 1$ passes through under the downstream side beacon 123 within the specified time since it passed through under the upstream side beacan 122. Incidentally, in the case of "only measurement information", the information of "travel distance from last passed beacon" may not be ancludcd.
2o Fig. 12 shows a structure of thus probe~car system.
In this system, an FCD information selection part 92 of an on-board un~.t 90 selects FCD information to be uploaded on the basis of the information of distance to the downstream side beacon included in measurement coding instructzox~ data z5 95. The other structure is identical to that of the first embodiment (Fig. 2).
_ _.. ."", CA 02480134 2004-09-O1 Fig. 13 shows a processing flow of this system.
The processings of step 1 to step :3 are the same as the processings,af the same steps of the processing flow (~'ig.
3) of the f~.xst embodiment.
s When the probe-car reaches the beacon, and an onw vehicle communication part 100 starts two-way commun.,zcation with a beacon communication part 87 (step 5), the FCD
information selection part 92 acquires information of the beacon number of the beacon 'through the on--vehicle to communication. part 100, refers to the measurement coding instruction data 95, reads information of distance to the beacon having the pext~.nent number, and compares this distance with th.e travel distance from the last passed beacon obtained at step 3 (step 51). Tn the case where ~.5 both. axe coincident with each other (Yes at step 52); it is determined that "only measurement in:Eormaf.ion" ( (3) of Fig.
11 ) is the FCD information, to be transmitted, and the FCD
information transmiss~.or part 91 transmits the d@termined "only measurement information" to the beacon (step 53). In, zo tk~e case where both are much different from each other (No at step 52), it is determined that "swept path +
measurement information" ((1) of Fig, 7.i) is the FCD
information to be transmitted, and the FCD information transmission part 91 transmits the determined "swept pafih +
z5 measurement information" to the bea con (step 59). After transmitting the FCD irzfox~mataon to the beacon, the on' board unit 90 resets the data stored ~.n a swept path measurement storage part 98 (step 55).
When receiving the ~'C~ anformation (step 20), the center apparatus 80 transmits new measurement and coding s instruction data 86 selected by a measurement coding instruction selection part 85 to the on-board unit 90. As shown by (2) of Fig. 11, the measurement and coding instruction data 8s includes the information of the number of the next beacon and the distance to the beacon (step ~.0 211). The on-board unit 90 reGe~.ves the new measurement and coding instruction data (step 56), and repeats the procedure from step J..
In the case where "swept path -~ measurement information" ((1) of Fig. 11) is received, the center is apparatus 80 refers to the pertxz~ent measurement and coding instruction data, decodes the coded data, and reproduces the measurement inforznataon on the swept path. In the case where "only measurement information°' ((3) of Fig. 11) is received, the center apparatus refers to the pertinent zo measurement and coding instruction data, decodes the ceded speed data, and reproduces the speed infox-mat~.on in which the installation route of the beacon is the swept path (step 22). The reproduced speed information is utilized for creation of traffic information .and the J.~.ke (step 23).
2s As stated above, in this system, even in the case where the probe-car runs while bypassing the installation route of beacons, it becomes possible for the center apparatus to utilize the measurement information measured by the an-board unit and the swept path information.
Although the judgment as to whether the probe-car s bypasses the installation route of the beacons is made by the on-board unit itseJ.fr in the case where the information of "travel distance from last passed beacon" is made to be included ix~ (J.l "on3.y measurement information", the center apparatus can check the propriety of the judgment of the zo on-board unit.
(Third Embodiment) In a probe-car systerct of a Lhird embodiment of the invention, similarly to the second embodiment, when an on ls boaxd unit of a probe-car having passed through under an upstream side beacon passes along a previously determined road and reaches a downstream side beacon, only measurement information is uploaded to the downstream side beacon, and when the on~-board unit passes along another xoad and za reaches the downstream side beacon, swept path data and measurement information axe uploaded to the downstream side beacon.
zn the system of the th~.xd embodiment, the upstream side beacon transmits a road network (road shape), which 25 leads to the downstream side beacon, to the on-board unit, so that the on-board unit itself can discriminate whether it has passed along the previously determine road. The on-board unit compares the road shape with the swept path, and fudges whether the route to the dawnstream side beacon is the previously determ~.n.ed road.
Fig. ~.4 exemplifies a data structure of data transmitted and received between the on-board unit and the beacon.
Data (1) "swept path + measurement information" is FCD information uploaded from the on-board una.t to the ao downstream side beacon when the probe-car 121 reaches the downstream side beacon without passing along the prev~.ously determined road, and is the same as the FCD information ((1) "swept path + measurement information") of the second embodiment (Fig. 11).
2s Data (2} "instruction informal ion to probe~car" is instruction information transmitted from the downstream s~.de beacon 122 to the on-board unit. This information includes the number of a downstream side beacon, and a data row composed of variab~.e length coded data of argument 2o predicted difference values expressing the road shape to the beacon, in addition to the beacon number of the beacon 122, instruction information of measurement method and coding method, and sampling distance interval of measurement zx~formation. The coded data of the road shape 2s is created by the method described in the forego~.ng <Creation of Running Locus Data>.
Data (3) "only measurement information" is FCD
information uploaded from the ors--board unit to the downstream side beacon when the probe-car 121 passes a7.ong the previously determined road and reaches the downstream s side beacon 123, and is tY~e same as the FCD information ((3) "only measurement information") of the second embodiment (Fig. 11).
The structure of the probe-car sxstem is the same as the second embodiment (~'ig. 12) .
~o Fig. 15 shows a processing flow of this system.
Processings of step 1 to step 3 are the same as the process~.ngs of the same steps zn the processing flow (Fig.
3) of the first embodiment.
The FCD information selection part 92 of the on-is board unit 90 refers to the measurement Coding instruct~.oz~
data 95, and compares the road shape to the downstream side beacon included therein with the swept path by map matching or the like. When they are coincident with each other, it is determined that (3) "only measurement information"
zo created at step 3 is to be transmitted as the FCD
information, and when they are n.ot coincident with each other, i t is detern~ir_ed that ( 1 ) "swept path t measurement information" created at step 2 is to be transmitted as t~:e FCD information (step 41)_ This operation is repeated z5 until the transmission timing occurs.
When the probe-car reaches i~he beacon and the on-vehicle apparatus communication part 100 starts the two-way communication with the beacon communication part 87 (step 5), the FCD information transmission part 9~. transmits the FCD information determined by the FCD information se7.ection s part 92 to the beacon (step 6). After transmitting the fC~7 information to the beacon, the on--board unit 90 resets the data stored in the swept path measurement information storage part 98 (step 61).
When receiving the FCD information (step 20), the to center apparatus 80 transmits the new measurement and coding instruction data 86 selected by th,e measurement coding instruction selection part 85 to the on-board unzt 90. As indicated by (2) of Fig. 1~~, the measurement and coding instructz.on. data 86 includes the numlaer of a next x5 beacon and the information indicating the road shape to the beacon (step 212). The on-board unit 90 receives the new measurement and coding instruction data (step 62), and repeats the procedure from step 1.
The center apparatus 80 reproduces the swept path zo and measurement information and utilizes it. This processing is the same as steps 22 and 23 in the processing flow (Fig. 13y of the secozad embodiment.
As stated above, the on-board unit of this system travels while judging whether the swept path is coincident z5 w~.th the previous7.y determined passage to the beacon. In the case where the on-board unit passes along the previously determined passage and reaches the beacon, it uploads only the measurement information to the beacon. rn the case where the on-board unit reaches the beacon without passing along the previously determined passage, it uploads the measurement infox~ation and the swept path to the beacon.
In this system. 3t is possible to accurately discriminate whether the probe-car passes along the previously determined passage, and accordingly, even in the io case where the probe~car passes along any route, the measurement information measured by the an~board unit can be effectively utilized.
As zs apparent from the above description, in the ~s probe-car system of the invention, the measurement information is effectively collected from the onboard unit by using the beacons, and can be effectively utilized.
Besides, the on-board unit of the invention can realize the probe-car system.
Description of the Related Art In recent years, an investigation has been made on the introduction of a probe-car system (also called a is floating car data (FCD) system) using a running vehicle as a s@nsor (probe) for collecting traffic information. In this system, an FCD on-vehicle apparatus installed in a vehicle records the speed of the vehicle and the swept path thereof, and transmits them to a center. In the center, za . measurement data transmitted from respective vehicles are analyzed to create road traffic information relating to traffic flow and the like.
Qatent document 1 (gyp-A-2002-269659) discloses a probe-car system in which a center specifies a collection zs area of FCD, an FCD on-vehicle apparatus of a vehicle running zn this area measures and stores a running position, a running speed az~d the like at every unit time, and the stored measurement data is transmitted to the center by usincr a cellular phone at e~rexy regular time S period.
However, in the probe-car system using the cellular phone, it becomes a serious problem who bears the communication cost. In the case where the center bears the communication cost, the cooperation of the FCD on~vehicle so apparatus side is easily obtained, and it is expected that a large amount of measurement data are collected. However, the burden of the center becomes severe. On the other hand, when the FGb on-vehicle apparatus side is forced to bear the communication cost, it becomes difficult to i5 collect a large amount of data.
Summary of the Invent.~.on The invention solves the conventional problem as stated above, and an object thereof zs to provide a probe~-2o car system in which beacons used for providing traffic information are utilized to efficiently collect measurement data from an FCD on~vehi.c~.e apparatus, and an apparatus for constructing the system.
A probe--car system of the invention includes an on-~s board unit of a probe-car which selects one of second z information of measurement information measured during running and road section xefererce data ~,ndicating a measurement section of the measurement informat~.on and first xn~ormation of the measurement information, and s uploads it to a beacon, and a center apparatus which collects the measurement information from the on-board unit of a probe-car through the beacon.
Besides, an on-board unit of a probe-car of the invention includes a communication unit for communicating ~.o with a beacon, an own vehicle position judgment unit for detecting own vehicle position, a sensor information collection unit fox collecting measurement information of a sensor, a storage unit for stor~.ng the measurement Information collected by the sensor information collection is unit and a swept path made of a sGt of the own vehicle position detected by the own position judgment unit, a coding process~.ng unit for transforming the measurement information and the swept path stored in the storage unit into coded data, an informat~.on transmission. unit for 2o transmitting the coded data of the one of ,the second information ~.~acluding the measurement ~.n,~ormation and the swept path arid the first information the rneasurernent information, to the beacon, when passing through the beacon, and an instructir~n informat~.on reception unit for as receiving instruction information including izzstructions of a measurement method of the measurement inforrna~tion and a coding method of the coded data from the beacon.
In this system, when the probe-car runs along an installation route of beacons and passes through under a downstream side beacon, only the measurement. information is s uploaded, so that the data amount of the measurement information can be increased, and the detazled measurement information can be transmitted. When the probe-car runs along a bypass and passes through under a downstreaza sl.de beacon, the swept path of the bypass and the measurement ~o information are uploaded. so that the center apparatus can utilize it as the measurement information of the bypass.
Brief Description of the Dxavafngs is Fig. 1 is a view showing a data structure of transm.itted/received data in a probe-car system according to a first embodiment of the invention;
Fig. 2 is a block diagram showing a structure of the probe~car system according to the first embodiment of 2o the invent~.ox~,;
Fig. 3 is a flow chart showing an operation of the probe-car system according to the first embodiment of the invention;
Fig. 4 is a view showing a relation between z5 ox~.g~.nal data and a first order scaling coefficient;
Fig. 5 is a view Showing a relation among first order, second order and third order scal.ang coefficients;
Fig. 6 ~.s a view showing gez~exal expressions of wavelet transform;
Flgs. 7A and '7B are views showing filter circuits for realizing AWE;
Fig. 8A is a view show~.ng separation of a signal in DWT and Fig. 8~ zs a view showing reconstruction of signals in IDW'F;
to Figs. 9A and ~B are views showing filter circu~.ts realizing the DWT and the IDWT in the first embodiment of the invention;
Figs. 10A to lOC are explanatory views of road section reference data;
is Fig. 11 zs a view showing a data structure of transmitted/xeceived data in a probe-car system according to a second embodiment of the ~.nvention:
Fig. 12 is a block diagram, showing a structure of the probe--car system according to the second embodiment of 20 the invent~o~l;
Fig. 13 is a flow chart showing an operation of 'the probe-car system according to the second embodiment of the invention;
Fig. 14 is a view showing a data structure of 2s transmitted/received data in a probe-car system according to a third embodiment of the invention; and Fig. 15 is a flow chart showing an operat~.oh of the probe-car system according to the third embodiment of the invention.
s In the drawings, a reference numeral 80 refers to a center apparatus; 81 to a swept path measurement information utilization part; 82 to a coded data decodi.n.g part; 83 to a fCD ~.nfoxznat~.on reception part; 84 to a measurement coding instruction transmission part; 8S to a to measurement coding instruction selection part; 86 to a measurement coding ar~stxuct~.on data; 87 to a beacorx communication part; 90 to an on-board unit of ~. probe-car;
91 to a FCD information transmission part: 92 to a FCD
informati.ox~ selection part; 93 to a coda-ng processing part:
is 94 to a measurement coding xnstxuct~.on reception part; 95 to a measuremEnt coding instruction data: 96 to a default measurement coding instruction data; 9'7 to an own vehicle position judgment part; 98 to a swept path measurement information storage part; 99 to a sensor information 20 COlleCtl.On part; 100 to an on-vehicle apparatus communication part; 101 to a GPS antenna;102 to a gyro; 106 to a sensor A; 107 to a sensor B; 108 to a sensor C; 121 to a probe-car; 122 to an u~astream side beacon; 123 to a downstream side beacon; 183 to a low-pass filter; 1,82 to a 2s high-pass filter; 18~ to a thznn~.ng circuit; 184 to a low-pass filter; 3.85 to a high-pass filter; 185 to a thinning circuit: Z87 to an adder circuit; 191 to a filter circuit:
192 to a filter circuat: and 193 to a filter circuit.
Detailed Descrzpgion o~ the preferred Embodiments xn a probe-car system of an embodiment of the invention, measurement information measured by a probe-car is collected through a beacon.
At present, beacons are installed an a road in order to provide VICS road traffic information to a passing vehicle at a pinpoint. The beacons have two Types, that io is, an optical beacon for a general road and a radio beacon for ar. expressway. For example, in the case of the optical beacon, two-way communication with an on-vehicle apparatus can be performed at a data transfer speed of 1 Mbps.
Although a distance between beaGOns varies according ~o an is installation state or the like, it is about several hundred m to several Km.
(First Embodiment) Tn a probe-car system of a first embodiment of the 2o invention, a swept path and measurement information of speed, fuel consumption and the like are measured by a probe-car, and when the probe-car first passes through under a beacon, or passes through under a next beacon after a specified time has passed since the probe-car passed z~ through under the last beacon for after running a specified ., distance or more), the measurement information and the swept Bath data are uploaded as FCD information from an on-board un~.t of a probe-car through the beacon. The scaept path data has a meaning as road section refex-ence data s indicating an object road section of the measurement infoxmat~.on.
A center apparatus haring received the FCD
information specifies the object road section of the measurement information from the swept path data, and utilizes the measurement information for the creation of traffic in:~ormation of the object road section.
When the probe-car passes through under the next bt~acon within the specified time since it passed through under the last beacon (or before it runs the specified' distance?, the travel distance and the number of the last passed beacon, togefi,her with the measurement information, are up~.oaded as the road section reference data from the on-board unit of a probe-car.
T'he center apparatus having received the FCD
2o inforinat~.on regards the probe-car as having run along the installation route of the beacons in a case where the travel distance and the installation distance between the beacons are substantially coincident with each other, and utilizes the measurement information for the creation of 2s the traffic information of the route. On the other hand, in the case where the travel distance and the installation distance between the beacons are much different from each other, the center apparatus rEgards the probe-car as having run slang a bypass, and stops the use of the measurement information.
s Respective processings will be described ~.n deta~.J..
<Cxeation of Running Locus Data>
position data at every regular distance L (for example, 20o m) is sampled from t~Ze posit~.on data measured so by the probe-car during running, the position data at the respective sampling points (.nodes) are arranged in seq~:ez~ce, and the node row is made the swept path data. and is transmitted to the center apparatus. At this time, in order to decrease the data amount of the swept path data, a is . following processing is performed.
First, 'the position data of a sampling point (node) is expressed by an argument 8 from an adjacent node. When a measurement start point or an end point is made a reference point, and the position of the reference point is zv specified by latitude and longitude, and when L is made canstant, the position of each node can be specified by only the argument 8. Next, the positian data is transformed into data haring a bias statistically. For tk~at purpose, when an argument from an adjacent node oz a z5 noticed node is made 8;, the position. data of the node is expressed by a difference between an argument predicted g value of the node predicted by using arguments 8~_~, and 6y_~
of preceding nodes (stat~.stical predicted value: for example, (8~_1 + 0~_2) !2) and the argument 8~ . l~ext, the data Qf the node row expressed by the argument predicted s difference value is subjected to variable length cod~.ng on the basis of a code tab3.e, and the coded data is transmitted to the center apparatus through the beacon.
when receiving the swept path data, the center apparatus decodes the coded data by using the same code so table, and decodes the arrangement of the position data of the nodes. Map matching of the arrangement of the nodes and the own map data is performed, and the swept path data of the probe-car i,s specified can the own map data.
is <Cx~eat~.on of Measurement Tnformation~
,Ia~.so with respect to the measurement information of speed, fuel cons~unptioz~ and the lilze, coding is made in order to reduce the data amount. l~ex~e, a descript~.on will be given. to a case where sampling data of the measurement zo information is supjected to discrete wavelet transform (DWT) to code the measurement information.
hig. 6 s~aows general expressions of the wavelet transform. The waveiet is a set of functions such as (mathematical expression 3) which is formed by performing z5 an operation (scale transform) of magnifying a function 'Y (t) , which is called a basic wavelet arid exists only in a 3. 0 limited range in time and frequency, by a factor of a on a time axis, or an operation {shift transform) of sh~,ft~.ng it by b in time. The firequenoy and time components of a signal corresponding to the parameters "a" and "b°' can be s extracted by using this function, and this operation is call the wavelet transform.
The waveJ.et transform zz~c7.udes a continuous wavelet transform and a discrete wavelet transform (DWT). The forward transform of the continuous wavelet transform is o expressed by (mathematical expression 1), and the inverse transform thereof is expressed by (mathematical expression 2), when the real numbers a and b are made a = 2j and b =
2jk ( j > 0) , the forward txaz~sform of the discrete wavelet transform is expressed by (mathematical expression 5), and u5 the inverse transform (IDWT) is expressed by {mathematical expression 6).
The DWT can be realized by a filter circuit for recursively d:.vidi.ng a J.ow frequency, and the wIDWT is realized by a filter circuit repeating synthesis inverse to zo the time of division. Fig. 7A shows the filter circuit of the DwT. The DWT circuit is constructed of plural caseade--connected circuits 19J., 192 and 193 each including a low pass filter 181, a high-pass filter 182, and a thinning circuit 183 fax thinning out signa~.s to J./2. The high zs frequency component of a signal inputted to the circuit 191 passes through the high-pass filter 182, is thi.nz~ed out by the thinning circuit to 1/2, and is outputted. The low frequency component thereof passes through the low--pass filter 181, is th~,nz~ed out by the thinning circuit to 1/2, and is inputted to the next cixcuit 192. Similarly, a~.sa s in the circuit 192, the high frequency component is thinned out and is outputted, and the low frequency component is thinned out, is inputted to the next circuit 193, and is similarly divided into a high frequency componer_t anal a low frequency component.
to Fig. 8A shows signals decomposEd by the respective circuits 191, 192 and 193 of the DWT circuit. An input signal f(t) (--- Ski°a; a superscript denotes the order) is divided in the circuit 193 into a signal. Wk;1? having passed through the high~pass filter 7.82 anci a signal Sk~l~ having is passed through the low-pass filter 1~~1. The signal. Sk~2~ is divided in the next circuit 92 into a signal wk~2? having passed through the high-pass filter 182 and a signal Sk{'~
having passed through the low pass filter 18v. The Sk~2~ is divided in the next circuit 193 zntc> a signal Wkt~~ having 2o passed through the high.-pass filter 182 and a signal Sk°3a having passed through the low-pass filter 187.. The S(t) is called a scaling coefficient (or low-pass filter), and W(t) is called a wave7.et coefficient (or high--pass filter) .
Next (mathematical expression B) and (mathematical. I
2s expression 9) indicate transform expressions of the DWT
usEd in the embodiment of the invention.
step 1: wt (t) - f (at~i) ~ C { f (2t) + f (2t~z) ~/2) (mathezn~atzca7. expression 8) step 2: s (t) - f (2t) + j (w(t) + w(t-1) + 2}/9]
(mathematical expression 8) s Tn the first order forward transform, sampling data of the measurement ~.nfoxmatian is made the discrete vaJ.ue f(t), and is transformed by the (mathematical expression 8) and the (mathematical expression 9) into the first order wavelet coefficient and the first order scaling so coefficient. zn a subsequent nth order forward transform, an (n-1)th order scaling coefficient is made f(t), and transform into an nth order waveiet coeff~.cient and nth order scaling coefficient is performed by the (mathematical expression 8) and the (mathematical expression 9). Fig, 9A
is shows a structure of each of the circuits 191, 192 and ?.93 of the DWT circuit reaiizing this transform. zn the drawing, "Round" indicates a rounding processing. The sampling data (state amount) of a traffic w state is transformed into the scaling coefficient and the wavelet zo coefficient by the (mathematical expression 8) and the (mathematical expression 9) and is p~.~ovided.
Fig. 7B shows a filter circuit of the IDWT. The TDWT circuit is con.stxucted of plural cascade-connected circu~.ts 194. 195 and 196 each including an interpolafiion zs circuit 186 for interpolating a signal by a factor of 2, a low-pass filter 184, a high-pass filter 185, and an adder 1~
187 for adding outputs of the low-pass filter 184 and the high-pass filter 185. Signals having a high frequency component and a low frequency component inputted to the circuit Z94 are interpolated by a factor of 2, are added to s each other, are inputted to the next circuit 295, are added with a high frequency component in this circuit 195, are further added with a high frequency component in the next circuit 195, and are autputted.
Fig. 8~ shows signals reconstructed by the circuits l0 194, 7.95 and 196 of the TDWx c~.rcuit:. In the circuit 194, the scaling coefficient Sk~3~ and the wavelet coefficient Wk~3~ are added to each other, so that the scal,~.ng coefficient Sk~Zf is created. In the next circuit 195, the sca7.ing coefficient Sk~2r and the wavelefi coefficient Wk~z~
xs are added to each other; so that the scaling coefficient Sksl~ is created. In the next circuit 196, the scaling coefficient Sk{1~ and the wavelet coefficient Wk«~ are added to each other, so that the Ski°' (= f(t)) is created.
Next (mathematical expression 10) and (mathematical 2o expression 11) indicate transform expressions of the TDWT
used in the embodiment of the inrrenti.on.
step ~.: f(~t) - s(t) + [~w(t) * w(t-1) ~- 2}/4~
(mathematical expression 10) step 2: f (2t*1y ~ w(t) - [~f(2t) * f(Zt+2) }/2a 25 (mathematical expression 11) Tn the nth order inverse transform, the signal f(t) transformed by (nø1)th order IDWT is made the scaling coefficient, and the transform with the stEps of the (raathEmatical expression 10) a~zd the (mathematical expression 11) is performed. Fig. 9~ shows a structure of each of the circuits 194, 195 and lg5 of the IDWT circuit for realizing this transform.
A.s stated above, from the sampling data of the measurement informat~.on, the scal.~.rag coefficient and the wavelet coefficient can be ca~.culated by the (mathematical so expressian $) and the (mathematical expression 9).
Besides, from the scaling coeffzc:ient and the wavelet coei~ficient, the sampling data of the measurement information. can be restored by the (mathematical expression 10) anal the (mathematical expression 17.) .
The first order scaling coefficient smoothes and indicates the shape expressed by the sampling data (original data), and the nth order scaling coeffic~.ent smoothes and indicates the shape expressed by the (n-~1~) th order scaling coefficient. In Fig. 4, the ~rertical axis 2o indicates speed, the horizontal axis indicates distance from a reference point, the sampling data of speed measured by the probe-car is indicated by a solid line, and the first scaling coefficient obtained when the original data is subjected the DWT once is indicated by a dotted line.
zs Fig. ~ shows the first scaling coeff~.cient (dotted line), a second scal~.ng coefficient (dashed line) obtained when the 7. 5 DWT is further repeated, and a third scaling coefficient tdotted line with long ling portions). The distance interval between the first order scaling coefficients is twice the distance interval of the original data, and the s value of the scaliing coefficient is an average of the values of the original data included in the distance interval. ?'he distance interval between. the nth order scalzng coefficients is twice the distance interval between the (n-1)th order scaling coefficients, and the value of to the nth order scaling coefficient i$ an average ofi the vaJ.ues of the (n-1)th order scaling coefficient included in the distance interval.
Accordingly, even in the case 'where the amount of data uploaded from the on-board unit of a probe--car is 15 limited, when data capable of restoring the nth (n ~ 1, 2, scaling coefficient as transz~itted, the center apparatus can grasp the rough state (coarse measurement information) of the measurement inf~~rmation,. ~As the order of the scaling coeffac~.ent becomes high, the amount of data ao transmitted from the on-board unit of a probe-car is decreased, and the measurement information which can be grasped by the center apparatus becomes coarse.
~cTransmitted/Reeeived Data Structuxe>
z5 Fig. 1 exemplifies a data structure of data transmitted and received between the on-board unit of a probe-car and the beacon.
When a probe-car i21 first passes through under a beacon 122, or passes through under the beacon 122 after a specified time has passed since it passed through under the s last beacon (or after it travels a specified distance), FCD
information ("swept path * measurement information'P) indicated by (1) is transmitted from the on-board unit of a probe-car to the beacon 122. The information includes the identification number of a code table used for encoding of ;o swept path, sampling distance interval of position information indicating the swept path, distance interval of the measurement information, coded data indicating the swept path, and coded data of the measurement information subjected to the DWT transform.
15 Since the position Information of the beacon 122 as the reference paint (end point) of the swept path is already known in the center apparatus, it is not necessary w that the position information of the reference point is w included in the data indicating the swept path.
zo Nevertheless, since the data amount of the coded data indicating the swept path is large, it is necessary to lessen the data amount of the coded data of the measurement information in the FCD Information c>f (1}. Thus, measures are taken such that only data necessary fox restoring the zs nth prdex scaling coefficient is made to be includEd, the sampling distance Interval of the measurement information is expanded to roughen the accuracy o~ the measurement information, or the distance of the sectzon as the object of the measurement information is narrowed.
~On the other hand, the beacon 7.22 downloads s ~.nstruction information indicated by (2) to the on-board unit of a probe-car passing through under the beacon 122.
The information includes the beacon number of the beacon 122, instruction information of the measurement method and coding method of the measurement information (information xo of the number of the measurement method and coding method previously transmitted to the on--board unit of a probe-car, and a code table used for coding), sampling distance znterval of the measurement information, and 'the like_ when the probe-car ~.2~. passes through under a ~s downstream side beacon 123 within the specifa.ed time since it passed through under the upstream side beaGOn 122 (or before it runs the specified distance), FCD information ("travel distance + measurement information") indicated by (3) is transmitted from the on-board unit of a probe--car to zo the beacon 123. This information inc3.udes the number of the last passed beacon 7.22, the travel distance from the ~.ast passed beacon x.22, the instruction number of the measurement method and cod~.ng method recei~red from th.e 'last passed beacon 122, the sampling distance interval of the 2s measurement information, and the coded data of the measurement information subjected to the DWT transform.
5i.nce the FCD information does not include the data o~ the swept path, the data amount c~f the coded data of the measurement information can be increased, and the infoxznation accuracy of the measurement information can be s raised.
.System Structure>
Fig. 2 shows a structure of this probe-car system.
This system includes an on-board unit 90 of a probe-car, ~o for measuring and providing data at the time of running, and a center apparatus 80 for collecting the data through a beacon. The beacon itself may have the structure of the center apparatus 80.
The onboard unit 90 ir.~cludes an on-~rehicle is apparatus com.~nunacatidn part 100 :Eor performing two-way communication with the beacon, a measurement coding instruction reception part 94 fox receiv~.ng ir_stxuction information. from the beacon, a~ sensor information cc~lleGti.on part 99 for collecting measurement ~.nformat~.on zo of a sensor A 10~ for detecting speed, a sensor H 107 for detecting power output, a sensor C 108 for detecting fuel consumption, and the like, an own vehicle position judgment part 9? for detecting own vehicle position by using GPS
information received by a GPS antenna 10~. and information zs of a gyro 102, a swept path measurement information storage part 98 for storing the swept path of the own vehicle and the measurement information of the sensors A, H and C, a coding processing part 93 for coding the measurement ~.nformation and sampling data of the swept path on the basis of instruction data 95 of the measurement method arid s coding method rece~.ved from the beacon and instruction data 96 of the default measurement method, and coding method pre~riously held by the on-board unit ~0, an FCD information selection part 92 for selecting whether the FCD information (1) of Fig. 1 is to be transmitted tc> the beacon or the FCD
to informata.on of (3) is to be transmitted, and an FCD
~.nformation transmission part 91 for. transmitting the FCb information selected by the FCD information selection part 92 to the beacar_ when passing through, under the beaGan.
pn the other hand, the center apparatus 80 includes 15 a beacon communication part 87 for perfarmin,g two-way communication with the on-board unit 90, an fD information reception part 83 for receiving the FC1~ information from the on-board unit 90, a coded data decoding part 82 for decoding the coded data included in the F'CD information, a 2o swept path measurement information utilizing part 81 for utilizing the data of the decoded measurement information and swept path, a measurement coding instruction selection part 85 for selecting measurement coding instruction data 86 to be gi~rer. to the on-board unit 90, and a measurement 25 COdl~I7g ~.nstruction transmission part 84 fior transmitting the selected measurement coding s.nstruct~.an data 86 to the on-board unit 90.
zn the center apparatus 80, there are prepared the plural measurement coding instruction data 86 made to correspond to traffic states and each including the s measurement method and coding method of the measurement information, the information of the code table, and the like. When the beacon communication part 87 starts the two-way communication with the on-board unit 90, the measurement coding instruction selection part 85 selects io the measurement coding instruction data 86 Corresponding to the present traffic state, arid the selected measurement coding instruction data 86 is transmitted to the on~bard unit 98.
is <Processing Flow>
dig. 3 shows a processing flow of the probe-car system. The on-board unit 90 measures present position and speed (measurement information) in a unit of, for example, one second, and stores the measurement data in the swept zo path measurement information storage part 98 (step 1). The coding processing part 93 creates sampling data of sampling distance interval of position information and creates coding data expressing the swept path from the stored swept path data in accordance with the measurement coding z5 instruction data 95 when the instruction data has been received from the beacon, or in accordance with the default measurement coding instruction data 96 if not so. Besides, the coding processing pant creates, from the stored speed information, the sampling data of sampling distance interval of the measurement infozmation, and creates coded data of speed information subjected to the CWT transform (step 2) .
text, the coding process~,nc~ part 93 creates th.e data of travel distance from the last passed beacon, and creates tk~e coded data o~ speed information subjected to so the DWT tr ansform ( step 3) .
The FCD information se~.ection part 92 counts up an accumulation counter for counting the accumulated value of distance (or time) froze the last passed beacon, and when the count value of the accumuJ.ation counter exceeds a is specified value, the "swept path ~ measurement information"
((1) of Fig. 1) created at step 2 is determined to be the transmission data. When the count value of the accumulat~.on counter is the specif~,ed value or less, the ~~travel distance + measurement information" ((3) of Fig. 1) 2o created at step 3 is determined to be the trans~uisszon data (step 9) .
In the case where the on-vehicle apparatus communication paxt 100 starts the communication w~.th the beacon coz~.munication. part 87, the FCD information z5 transmission part 9J. judges that the timing of transmission occurs (step 5), and transmits the FCA information selected by the FCD information selection part 92 to the beacon (step 6) . When the tiz~,ing of transmission does not occur, the procedure from step ~. is repeated.
After transmitting the FCD information to the s beacon, the on-board unit 90 resets the accumulation .counter, and resets the data stored in the swept path measurement information storage part 98 (step 7).
When receiving the FCD a.nformation (step 20), the cex~tex apparatus 80 transmits the new measurement and io coding instruction data 86 selected by the mEasurernent coding instruction selection part 85 to the on-board unit 90 (step 21). The on,-board unit 90 receives the new measurement coding instruction data (step 8), and repeats the procedurE from step 1.
is In the case where "swept path a~ trie~.sur ement information" ((1) of Fig. I) is received, the center apparatus 80 refers to the pertinent measurement and coding instruction data, decodes the coded data, and reproduces the measurement information on the swept path. In the case zo where "travel distance + measurement information" ((3) of Fig. 2) is received, the center apparatus refers to the travel distance and the beacon number included in the FCD
information. When the installation interval between the upstream side beacon and the downstream side beacon is 2s substantially coincident with the travel. distance, the center apparatus refers to the pertinent measurement and coding instruction data, decodes the coded speed data, and reproduces the speed information whi3e the installation route of beacons is made the swept path (step 22).
The center apparatus 80 utilizes the reproduced s speed information for creation of the traffic information and the like (step 23).
As stated above, in the probe-car system, the FCD
information can be efficiently collected from the on-board unit by using the beacon.
io Modified Example>
Although the description has been given to the case where the variable 2ength coding system of an argument predicted difference value is applied to the coding of the is swept path data, and the coding system by DWT is applied to the coding of the measurement information, the invention is not limited to this. The measurement information can be coded by the variable length coding system of the argument predicted difference value, and the swept path data can be zo coded by the DWT. Besides, it is also possible to use orthogonal transform such as DFT (discrete Fouriex transform), DGT idiscrete cosine transform), DHT (discrete Hadamard transform), or DWT (discrete wavelet transform).
Besides, although the description has been given to 2s the case where the measurement and coding instruction data is downloaded from the beacon to the on-board unit, this is not inevitabJ.e, Besides, a~.though the description has beer. given to the case where the swept path data is transmitted as the road section reference data ind~.ca,ting the object z~oad s section of the measurement information, the road section reference data may be othexs» For example, as shown in Fig. 10A, un~.formly determined road section identifiers (link number) and intersection identifiers (node number) may be used.
to zz~ the case where both the on-board unit and the center apparatus refer to the same map, the on-board unit transmits the latztude and longitude data of the measurement start ~aoint on the map to the center apparatus, and the center apparatus can specify the road section based on this data.
Besides, as shown in fig< IO:B, the abject road may be transmitted by transmi.tt~.ng latitude and longitude data (including the attribute information of name, kind of road and the 7.zke as well) for position reference of zg interm~.ttent nodes P1, P2, 1~3 and P~~, which are extracted from intersection parts and roads at midpoints in the link, to the centex apparatus. Here, the nodes are as follows:
P1 - link center point, P2 = zr~tersection part, p3 = 1. ink center point, and P4 = link center point. Zn this case, as zs Shawn i.n Fig. IOC, the oenter apparatus specifies the respective positions of Pl, P2, P3 and P4, and next, COhneCt9 the respective sections by a route search to specify the cbject road section.
Besides, as the road section reference data fox specifying the object raad, a road map is divided into s tile-~li.ke parts, and identifiers attached to the respective ones, kilo posts provided on the road, road name, address, zip code and the ZiJ~e may be used.
Movement distance, movez~ent time, exhaust gas information, wiper operation state, parking brake operation la state and the like in addition to the speed, the power output, and the fuel consumption can be included in the measurement informatian.
(Second ~mbodzment) xs In a probe-car system of a second embodiment of the invention, when a an--board unit of a probe-car having passed through under an upstream side beacon passes along a previous3y determined xoad and reaches a~ downstream side beacon, only measurement information is uploaded to the za downstream side beacon, and when passing along another road and reaching the downstream s~.de beacon, swept path data and the measurement information are uploaded to the downstream side beacon. In order to enable the on-board unit itself to discrim~.nate whether it has passed along the z5 previously determined road, the upstxeam side beacon transmits the number of the downstream side beacon and the distance to the downstream side beacon to the on-board unit. When the on-board unit reaches the downstream side beacon, in the case where the travel distance is substantially coincident with the distance to the s downstream .side beacon transmitted from the upstream side beacon, the on-board unit discrimina°tes that it has passed along the previously determined road, and when the travel distance is much different from the dzstance to the downstream side beacon transmitted from upstream side so beacon, the on-board unit discriminates that it has not passed along the prev~.ous3y deterrnine:d road.
Fig. 17. exemplifies the data structure of data transmitted and received between the on-board unit and the beacon.
Data (1) "swept path * measurement z,nformation~~ is FCD information uploaded from the on-board unit to the downstream side beacon ~.2~ when the probe~car 121 reaches the downstxeaxn side beacon 123 without passing along the prev~.ously determined road. This is the same as the FCD
zo information transmitted from the on-board unit fid the beacon 122 in the fzrst embodiment (~'ig. ~.) when the probe-car ~.2~, first passes through under the beacon I,22, or passes through u_~nder the beacon 122 after the specified time has passed since it passed thxough under the last 2s beacon (or after it runs the specified distance or more).
Data (2) "instruction informat~.oz~ to probe-car" is - CA 02480134 2004-09-O1 - . , ,."
~.nstruction information transmitted from the downstream side beacon 122 to the on-board unit. 'this informati.an includes information of the number of the downstream side beacon 123, and the distance to the beacon 123 in additior_ s to the beacon number of the beacon 122, instruction information of x~.easurement method and cading method, and saz~pli,ng distance interval of measurement informatian.
Data (3) "only measurement information" is FC1~
informati.an upJ.oaded from the on-board unit to the to downstream side beacon 123 when the pxobe-car 121 passes along the pre~riously determined road and reaches the downstream side beacon 123. This is the same as the FCD
iz~foxzn.ation. transmitted to the downstream side beacon 123 in the first embodiment (Fig. 1) when the probe~car 121 1$ passes through under the downstream side beacon 123 within the specified time since it passed through under the upstream side beacan 122. Incidentally, in the case of "only measurement information", the information of "travel distance from last passed beacon" may not be ancludcd.
2o Fig. 12 shows a structure of thus probe~car system.
In this system, an FCD information selection part 92 of an on-board un~.t 90 selects FCD information to be uploaded on the basis of the information of distance to the downstream side beacon included in measurement coding instructzox~ data z5 95. The other structure is identical to that of the first embodiment (Fig. 2).
_ _.. ."", CA 02480134 2004-09-O1 Fig. 13 shows a processing flow of this system.
The processings of step 1 to step :3 are the same as the processings,af the same steps of the processing flow (~'ig.
3) of the f~.xst embodiment.
s When the probe-car reaches the beacon, and an onw vehicle communication part 100 starts two-way commun.,zcation with a beacon communication part 87 (step 5), the FCD
information selection part 92 acquires information of the beacon number of the beacon 'through the on--vehicle to communication. part 100, refers to the measurement coding instruction data 95, reads information of distance to the beacon having the pext~.nent number, and compares this distance with th.e travel distance from the last passed beacon obtained at step 3 (step 51). Tn the case where ~.5 both. axe coincident with each other (Yes at step 52); it is determined that "only measurement in:Eormaf.ion" ( (3) of Fig.
11 ) is the FCD information, to be transmitted, and the FCD
information transmiss~.or part 91 transmits the d@termined "only measurement information" to the beacon (step 53). In, zo tk~e case where both are much different from each other (No at step 52), it is determined that "swept path +
measurement information" ((1) of Fig, 7.i) is the FCD
information to be transmitted, and the FCD information transmission part 91 transmits the determined "swept pafih +
z5 measurement information" to the bea con (step 59). After transmitting the FCD irzfox~mataon to the beacon, the on' board unit 90 resets the data stored ~.n a swept path measurement storage part 98 (step 55).
When receiving the ~'C~ anformation (step 20), the center apparatus 80 transmits new measurement and coding s instruction data 86 selected by a measurement coding instruction selection part 85 to the on-board unit 90. As shown by (2) of Fig. 11, the measurement and coding instruction data 8s includes the information of the number of the next beacon and the distance to the beacon (step ~.0 211). The on-board unit 90 reGe~.ves the new measurement and coding instruction data (step 56), and repeats the procedure from step J..
In the case where "swept path -~ measurement information" ((1) of Fig. 11) is received, the center is apparatus 80 refers to the pertxz~ent measurement and coding instruction data, decodes the coded data, and reproduces the measurement inforznataon on the swept path. In the case where "only measurement information°' ((3) of Fig. 11) is received, the center apparatus refers to the pertinent zo measurement and coding instruction data, decodes the ceded speed data, and reproduces the speed infox-mat~.on in which the installation route of the beacon is the swept path (step 22). The reproduced speed information is utilized for creation of traffic information .and the J.~.ke (step 23).
2s As stated above, in this system, even in the case where the probe-car runs while bypassing the installation route of beacons, it becomes possible for the center apparatus to utilize the measurement information measured by the an-board unit and the swept path information.
Although the judgment as to whether the probe-car s bypasses the installation route of the beacons is made by the on-board unit itseJ.fr in the case where the information of "travel distance from last passed beacon" is made to be included ix~ (J.l "on3.y measurement information", the center apparatus can check the propriety of the judgment of the zo on-board unit.
(Third Embodiment) In a probe-car systerct of a Lhird embodiment of the invention, similarly to the second embodiment, when an on ls boaxd unit of a probe-car having passed through under an upstream side beacon passes along a previously determined road and reaches a downstream side beacon, only measurement information is uploaded to the downstream side beacon, and when the on~-board unit passes along another xoad and za reaches the downstream side beacon, swept path data and measurement information axe uploaded to the downstream side beacon.
zn the system of the th~.xd embodiment, the upstream side beacon transmits a road network (road shape), which 25 leads to the downstream side beacon, to the on-board unit, so that the on-board unit itself can discriminate whether it has passed along the previously determine road. The on-board unit compares the road shape with the swept path, and fudges whether the route to the dawnstream side beacon is the previously determ~.n.ed road.
Fig. ~.4 exemplifies a data structure of data transmitted and received between the on-board unit and the beacon.
Data (1) "swept path + measurement information" is FCD information uploaded from the on-board una.t to the ao downstream side beacon when the probe-car 121 reaches the downstream side beacon without passing along the prev~.ously determined road, and is the same as the FCD information ((1) "swept path + measurement information") of the second embodiment (Fig. 11).
2s Data (2} "instruction informal ion to probe~car" is instruction information transmitted from the downstream s~.de beacon 122 to the on-board unit. This information includes the number of a downstream side beacon, and a data row composed of variab~.e length coded data of argument 2o predicted difference values expressing the road shape to the beacon, in addition to the beacon number of the beacon 122, instruction information of measurement method and coding method, and sampling distance interval of measurement zx~formation. The coded data of the road shape 2s is created by the method described in the forego~.ng <Creation of Running Locus Data>.
Data (3) "only measurement information" is FCD
information uploaded from the ors--board unit to the downstream side beacon when the probe-car 121 passes a7.ong the previously determined road and reaches the downstream s side beacon 123, and is tY~e same as the FCD information ((3) "only measurement information") of the second embodiment (Fig. 11).
The structure of the probe-car sxstem is the same as the second embodiment (~'ig. 12) .
~o Fig. 15 shows a processing flow of this system.
Processings of step 1 to step 3 are the same as the process~.ngs of the same steps zn the processing flow (Fig.
3) of the first embodiment.
The FCD information selection part 92 of the on-is board unit 90 refers to the measurement Coding instruct~.oz~
data 95, and compares the road shape to the downstream side beacon included therein with the swept path by map matching or the like. When they are coincident with each other, it is determined that (3) "only measurement information"
zo created at step 3 is to be transmitted as the FCD
information, and when they are n.ot coincident with each other, i t is detern~ir_ed that ( 1 ) "swept path t measurement information" created at step 2 is to be transmitted as t~:e FCD information (step 41)_ This operation is repeated z5 until the transmission timing occurs.
When the probe-car reaches i~he beacon and the on-vehicle apparatus communication part 100 starts the two-way communication with the beacon communication part 87 (step 5), the FCD information transmission part 9~. transmits the FCD information determined by the FCD information se7.ection s part 92 to the beacon (step 6). After transmitting the fC~7 information to the beacon, the on--board unit 90 resets the data stored in the swept path measurement information storage part 98 (step 61).
When receiving the FCD information (step 20), the to center apparatus 80 transmits the new measurement and coding instruction data 86 selected by th,e measurement coding instruction selection part 85 to the on-board unzt 90. As indicated by (2) of Fig. 1~~, the measurement and coding instructz.on. data 86 includes the numlaer of a next x5 beacon and the information indicating the road shape to the beacon (step 212). The on-board unit 90 receives the new measurement and coding instruction data (step 62), and repeats the procedure from step 1.
The center apparatus 80 reproduces the swept path zo and measurement information and utilizes it. This processing is the same as steps 22 and 23 in the processing flow (Fig. 13y of the secozad embodiment.
As stated above, the on-board unit of this system travels while judging whether the swept path is coincident z5 w~.th the previous7.y determined passage to the beacon. In the case where the on-board unit passes along the previously determined passage and reaches the beacon, it uploads only the measurement information to the beacon. rn the case where the on-board unit reaches the beacon without passing along the previously determined passage, it uploads the measurement infox~ation and the swept path to the beacon.
In this system. 3t is possible to accurately discriminate whether the probe-car passes along the previously determined passage, and accordingly, even in the io case where the probe~car passes along any route, the measurement information measured by the an~board unit can be effectively utilized.
As zs apparent from the above description, in the ~s probe-car system of the invention, the measurement information is effectively collected from the onboard unit by using the beacons, and can be effectively utilized.
Besides, the on-board unit of the invention can realize the probe-car system.
Claims (11)
1. A probe-car system comprising:
an on-board unit of a probe-car;
a first beacon; and a center apparatus, wherein said on-boar unit uploads at least one of:
first information including measurement information measured while the probe-car is moving;
and second information including said measurement information and read section reference data indicating a measurement section of the measurement information, to said first beacon, and wherein said center apparatus collects the measurement information from the on-board unit of a probe-car through the beacon.
an on-board unit of a probe-car;
a first beacon; and a center apparatus, wherein said on-boar unit uploads at least one of:
first information including measurement information measured while the probe-car is moving;
and second information including said measurement information and read section reference data indicating a measurement section of the measurement information, to said first beacon, and wherein said center apparatus collects the measurement information from the on-board unit of a probe-car through the beacon.
2. The probe-car system according to claim 1, further comprising:
a second beacon in upstream side, which the probe-car last passed, wherein said on-board unit compares a travel distance or a driving time from said second beacon with a previously set threshold, if the travel distance or the driving time exceeds the threshold, said on-board unit uploads the second information to the first beacon, and if the travel distance or the driving time is not larger than the threshold, said on-board unit uploads the first information to the first beacon.
a second beacon in upstream side, which the probe-car last passed, wherein said on-board unit compares a travel distance or a driving time from said second beacon with a previously set threshold, if the travel distance or the driving time exceeds the threshold, said on-board unit uploads the second information to the first beacon, and if the travel distance or the driving time is not larger than the threshold, said on-board unit uploads the first information to the first beacon.
3. The probe-car system according to claim 2, wherein said first information further includes the beacon number of said second beacon and the travel distance from said second beacon, and wherein said center apparatus compares a road distance between said first beacon and said second beacon with the travel distance, and determines whether or not the measurement information an the first information is adopted.
4. The probe-car system according to claim 2, further comprising:
a third beacon in a downstream side, wherein said on-board and downloads a distance between said first beacon and said third beacon from said first beacon, and compares the downloaded distance with a travel distance to said third beacon, if said downloaded distance is approximately same to sand travel distance, said on-board unit uploads the first information to said first beacon, and if said downloaded distance is not approximately same to said travel distance, said on-board unit uploads the second information to said first beacon.
a third beacon in a downstream side, wherein said on-board and downloads a distance between said first beacon and said third beacon from said first beacon, and compares the downloaded distance with a travel distance to said third beacon, if said downloaded distance is approximately same to sand travel distance, said on-board unit uploads the first information to said first beacon, and if said downloaded distance is not approximately same to said travel distance, said on-board unit uploads the second information to said first beacon.
5. The probe-car system according to claim 1, further comprising:
a third beacon in a downstream side, wherein said on-board unit downloads road section reference data indicating a road section to a downstream side beacon from said first beacon, and compares the downloaded road section reference data with a swept path to said third beacon, if the probe-car run along the road section indicated by the road section reference data, said on-board unit uploads said first information to the first beacon, and if the probe-car run along a road section other than the road section indicated by the road section reference data, said on-board unit uploads said second information to said first beacon.
a third beacon in a downstream side, wherein said on-board unit downloads road section reference data indicating a road section to a downstream side beacon from said first beacon, and compares the downloaded road section reference data with a swept path to said third beacon, if the probe-car run along the road section indicated by the road section reference data, said on-board unit uploads said first information to the first beacon, and if the probe-car run along a road section other than the road section indicated by the road section reference data, said on-board unit uploads said second information to said first beacon.
6. The probe-car system according to claim 1, wherein said on-board unit uploads, as the road section reference data, coded data obtained by coding position information on a swept path at every regular distance, and wherein said center apparatus decodes the coded data, restores the position information, and specifies the measurement section of the measurement information.
7. The probe-car system according to claim 5, wherein said on-board unit downloads coded data obtained by coding position information on the read section at every regular distance, as the road section reference data indicating the road section to the third beacon, restores the position information by decoding said coded data, and compares the position information with the swept path.
8. The on-board unit of a probe-car comprising:
a communication unit for communicating with a beacon:
an own vehicle position judgment unit for detecting own vehicle position;
a sensor information collection unit for collecting measurement information of a sensor;
a storage unit for storing the measurement information collected by the sensor information collection unit and a swept path made of a set of the own vehicle position detected by the own vehicle position judgment unit;
a coding processing unit for transforming the measurement information and the swept path stored in the storage unit into coded data;
an information transmission unit for transmitting the coded data of the one of a first information including said measurement information and a second information including said measurement information and the swept path, to the beacon, when passing through the beacon; and an instruction information reception unit for receiving instruction information including instructions of a measurement method of the measurement information and a coding method of the coded data from the beacon.
a communication unit for communicating with a beacon:
an own vehicle position judgment unit for detecting own vehicle position;
a sensor information collection unit for collecting measurement information of a sensor;
a storage unit for storing the measurement information collected by the sensor information collection unit and a swept path made of a set of the own vehicle position detected by the own vehicle position judgment unit;
a coding processing unit for transforming the measurement information and the swept path stored in the storage unit into coded data;
an information transmission unit for transmitting the coded data of the one of a first information including said measurement information and a second information including said measurement information and the swept path, to the beacon, when passing through the beacon; and an instruction information reception unit for receiving instruction information including instructions of a measurement method of the measurement information and a coding method of the coded data from the beacon.
9. The on-board unit of a probe-car according to claim 8, wherein the information transmission unit compares a travel distance or a driving time from a last passed upstream side beacon with a previously set threshold, if the travel distance or the driving time exceeds the threshold, transmits the second information, and if the travel distance or the driving time is not larger than the threshold, transmits the first information.
10. The on-board unit of a probe-car according to claim 8, wherein the instruction information reception unit receives, as the instruction information, instruction information including information of a distance to a downstream side beacon, wherein the information transmission unit compares the distance included in the instruction information with a travel distance to the downstream side beacon, if said received distance is approximately same to said travel distance, transmits said first information, and if said received distance is not approximately same to said travel distance, transmits said second information.
11. The on-board unit of a probe-car according to claim 8, wherein said instruction information reception unit receives, as the instruction information, instruction information including information indicating a road section shape to a downstream side beacon, wherein the information transmission unit compares the road section shape to the downstream side beacon included in the instruction information with the swept path, if said probe-car ran a road section indicated by the road section shape, transmits the first information, and if said probe-car ran a road section other than the road section indicated by the road section shape, transmits the second information.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002480134A CA2480134A1 (en) | 2004-09-01 | 2004-09-01 | Probe-car system using beacon and apparatus therefore |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002480134A CA2480134A1 (en) | 2004-09-01 | 2004-09-01 | Probe-car system using beacon and apparatus therefore |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2480134A1 true CA2480134A1 (en) | 2006-03-01 |
Family
ID=35997717
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002480134A Abandoned CA2480134A1 (en) | 2004-09-01 | 2004-09-01 | Probe-car system using beacon and apparatus therefore |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2480134A1 (en) |
-
2004
- 2004-09-01 CA CA002480134A patent/CA2480134A1/en not_active Abandoned
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